This invention relates to connections for concrete members to be joined together with a structure during the process of erection.
Generally, an insert is placed into a body of concrete during the casting of the concrete. It is then held in place until the concrete hardens. This creates a portion of a connection that will serve to hold the concrete member onto an inner structure to form a completed structure.
Typically, the connection is formed by connecting a continuously threaded rod to a slot in the insert; for example, a nut and bolt may be used. This slot is usually parallel to the insert's longitudinal axis. The slot allows a tolerance vertically or horizontally to allow for the face of the member to align with another and to allow for normal expansion and contraction of the structure.
A different type of attachment device uses a piece of flat steel referred to as a strap. It is inserted into the body of the device and welded to the inner structure.
As noted above, the adjustable inserts can allow for expansion and contraction of the concrete. The connection is made so the bolt and nut are not tightened to the maximum amount so that when the concrete expands and contracts the connections can remain intact.